Process for halogenating carboxylic acids

ABSTRACT

A process for chlorinating or brominating a carboxylic acid which involves heating a carboxylic acid with chloride ions or bromide ions and molecular oxygen in the presence of nitrate ions, a carboxylic acid anhydride and a heavy metal cation. Acetic acid is converted to chloroacetic acid.

United States Patent Inventor Charles M. Selwltz Monroevllle, Pa. Appl.No. 92,938 Filed Nov. 25, 1970 Patented Dec. 14, 1971 Assignee GullResearch Development Company Pittsburgh, Pa.

PROCESS FOR HALOGENATING CARBOXYLIC ACIDS 12 Claims, No Drawings u.s. Cl260/539 A, 260/408, 260/539 R int. Cl ..C07c 53/16, c07 53/32 Field ofSearch..' 260/539 R, 5 39 A, 408

[56] References Cited UNITED STATES PATENTS 2,688,634 9/1954 Pinkston260/539 A 3,352,907 11/1967 Reichenider et al 260/539 R 3,152,17410/1964 Morris et al. 260/539A 3,363,010 1/1968 Schwarzenbec 260/515 APrimary Examiner- Lorraine A. Weinberger Assistant Examiner-JacquelineL. Davison AnomeysMeyer Neishloss, Deane E. Keith and Donald L.

Rose

PROCESS FOR HALOGENA'IING CARBOXYLIC ACIDS This invention relates to aprocess for chlorinating or brominating a carboxylic acid.

1 have discovered that chlorination or bromination of a carboxylic acidcan be advantageously effected with chloride ions or bromide ions if thereaction is carried out in the presence of nitrate ions, molecularoxygen, a carboxylic acid anhydride and a heavy metal salt. Sincechloroacetic acid is the most commercially important halogenatedcarboxylic acid, this process is of particular value in the chlorinationof acetic acid to chloroacetic acid.

The carboxylic acid that can be halogenated hereunder contains from twoto about 20 carbon atoms, preferably two to about six carbon atoms. Thisincludes acetic acid, propionic acid, butyric acid, isobutyric acid,valeric acid, isovaleric acid, caproic acid, isocaproic" acid, heptanoicacid, caprylic acid, pelargenic acid, capric acid, decanoic acid,undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmiticacid, stearic acid, arachidic acid. The carboxylic acid can be used inexcess in this reaction in order to serve as a solvent for the othercomponents. I

There must be present in the reaction system chloride ions or bromideions to halogenate the carboxylic acid defined above. By "chloride ionsor bromide ions" 1 mean a singly negatively charged chlorine or bromineatom. Although the chloride ion or bromide ion canbe obtained from manycompounds, desirably such ion is obtained from a compound that isreadily capable of dissociating in the present reaction system tochloride or bromide ions, such as hydrogen chloride, hydrogen bromide,ammonium chloride, ammonium bromide, organic chlorides and bromides,such as aniline hydrochloride, methyl amine hydrochloride, benzyltrimethyl ammonium bromide and metallic chlorides and bromides, such assodium chloride, potassium bromide, rubidium chloride, magnesiumbromide, cupric chloride, barium chloride, calcium chloride, aluminumbromide, etc. Of these I prefer to use hydrogen chloride or hydrogenbromide. The amount of chloride or bromide ion present in the systemrelative to the carboxylic acid on a molar basis can be, for example,from about 2:1 to about 1:20, preferably from about 1:2 to about 1:10;however, in the preferred procedure the carboxylic acid is used insubstantial excess to serve as a reaction solvent. For this reasonproduct yield and relative proportions are based upon the halogenpresent.

In order to obtain the desired conversion herein it is imperative thatthe above materials be brought into contact with each other in thepresence of nitrate ions. Any compound which by ionization, oxidationor-disproportionation under the reaction conditions defined herein willresult in the production of nitrate ions can be employed. By nitrateions I mean to include N0, a singly charged anion containing onenitrogen atom and three oxygen atoms. Examples of compounds that can beemployed include nitric acid, sodium nitrate, cesium nitrate, etc. Ofthese I prefer to employ nitric acid. The amount of nitrate ion employedon a molar basis, relative to the halogen charge, can be from about 1:5to about 1:20, preferably from about 1:2 to about 1:1,000.

Also required in the reaction system is a lower carboxylic acidanhydride derived from carboxylic acids having from two to six carbonatoms, preferably from two to three carbon atoms. Examples of carboxylicacid anhydrides that can be employed include acetic anhydride, propionicanhydride, butyric anhydride, isobutyric anhydride, cyclobutylcarboxylic acid anhydride, hexanoic anhydride and the like. The amountof carboxylic acid anhydride employed can be from about 1:2 to about1:100 mols, preferably from about 1:3 to about 1:10 mols, per mol ofhalogen charge.

As defined above, the reaction is carried out in the presence ofmolecular oxygen. When this is done, less nitrate ion is required andconversion of carboxylic acid is increased. The amount of molecularoxygen that can be employed relative to the halogen, on a molar basis,can be from about 2:1 to-about 1:6, preferably from about 1:1 to about1:3.

Rates of reaction are increased by additionally having present in thereaction system a substance selected from the group consisting ofcopper, manganese, cerium, cobalt, vanadium, chromium, iron, nickel,cadmium, tin, antimony, mercury, bismuth, the noble metals and compoundsof these metals. Examples of compounds that can be employed hereininclude metallic iron, ferric acetate, ferric propionate, ferric hydroxyacetate, ferric chloride, ferric hydroxide, ferric nitrate, ferricphosphate, ferric sulfate, ferrous acetate, ferrous nitrate, ferrouslactate, ferrous bromide, palladium, rhodium, iridium, osmium,ruthenium, platinum, rhodium formate, palladium acetate, palladiumpropionate, iridium butyrate, palladium pivalate, palladium octanoate,osmium isooctanoate, palladium benzoate, palladium laurate, rutheniumstearate, palladium isobutyr'ate, palladium para-toluate, platinumgamma-chlorobutyrate ruthenium tetracontanoate, osmium phenyl-acetate,iridium cyclohexane carboxylate, rhodium crotonate, palladium furoate,palladium heptanoate, palladium eicosanoate, palladium chloride,palladium nitrate, palladium oxide, rhodium bromide, iridium sulfate,osmium cyanide, ruthenium perchlorate, rhodium iodide, platinumfluoride, platinum phosphate, platinum pyrophosphate, ruthenium oxide,platinic bromide, platinous bromide, platinum oxide, platinous cyanide,platinum hydroxide, rhodium sulfate, rhodium oxide, osmium tetroxide,ruthenium trichloride, iridium oxide, metallic copper, cupric nitrate,cuprous chloride, cupric acetate, manganese, manganic oxide, manganeseacetate, cerium, cerous nitrate, ceric ammonium sulfate, cobalt,cobaltous bromide, cobaltous fluoride, cobaltous perchlorate, cobalticchloride, vanadium, vanadium pentoxide, vanadium dichloride, vanadiumpentafluoride, vanadyl bromide, chromium, chromium trioxide, chromicacetate, nickel, nickel acetate, nickel nitrate, cadmium, cadmiumperchlorate, cadmium, manganate, tin, tin tetrachloride, tintrifluoride, tin sulfate, antimony, antimony chloride, antimonybutyrate, mercury, mercuric acetate, mercuric nitrate, bismuth, bismuthphosphate, bismuth arsenate, bismuth oxychloride, etc.

A noble metal compound or copper compounds is preferred, and mostpreferred is a carboxylic acid salt of the metal. Thus, the cationicportion of the salt can be copper or one of the defined noble metalssuch as palladium, while the anionic portion thereof can be derived fromthe group of carboxylic acids, straight and branched chain, having fromone to 40 carbon atoms, preferably from two to six carbon atoms,examples of which have been identified above. The amount of metal, orcompounds thereof, as metal, on a molar basis relative to halogen,employed can range from about 0.0001 percent to about 10 percent,preferably from about 0.1 percent to about 5 percent.

As to reaction conditions, the temperature can be from about to aboutC., preferably from about 60 to about 120 C., the presence from about0.5 to about 5,000 pounds per square inch gauge, preferably from about10 to about 500 pounds per square inch gauge, and the reaction time fromabout 0.5 to about 50 hours.

At the end of the reaction period the halogenated carboxylic acidproduced, which can carry one or more halogens thereon, can be recoveredfrom the reaction mixture in any suitable manner, for example, bydistillation. Depending upon their boiling points, the individualcomponents in the reaction mixture, including the desired chloro orbromo carboxylic acid, will come off individually overhead an can thusbe easily recovered.

The process of the invention can further be illustrated by thefollowing. A series of reaction mixtures were made up using 119.3 gramsof acetic acid, 4.0 grams of 70 percent aqueous nitric acid and thecomponents identified in table 1. A series of runs were carried out inwhich the reaction mixture was placed in a ZOO-milliliter, thick-walledglass reactor, provided with a magnetic stirrer. In each run the mixturewas heated to a predetermined temperature level and oxygen was suppliedto the reactor to maintain a pressure of pounds per square inch gaugethroughout the reaction period. At the end of each run the reactor wascooled, depressured and the contents removed for analysis. The resultsobtained are tabulated below in table I. in each run analysis was by gaschro- I claim:

11. A process for preparing a halogenated carboxylic acid selected fromthe group consisting of chloro carboxylic acids and bromo carboxylicacids which comprises heating a carboxylic acid having at least twocarbon atoms and up to about 20 carbon atoms with a halogen ion selectedfrom the group consisting of chloride ions and bromide ions, a nitrateion, molecular oxygen, at lower carboxylic acid anhydride and a materialselected from the group consisting of copper, manmatography.

TABLE I Run 1 2 3 4 5 s Pd(0Ac) g 1.12 1.12 1.12 Cu 0Ac)g, g 3. 63 8. 63

304, g 8. 9 Acetic anhydride, 10 10 10 Cl, mmols 420 364 285 417 321 461 72 31 148 120 140 120 120 120 120 120 Time, hours 2. 26 3.6 4.0 3. 56. 0 6.0 Chloroacetic acid:

G 9.2 9.1 9.8 22.1 19.6 98 96 104 234 208 Yield, percent 23 27 37 57 651 Percent yield based on HC] reacted.

a-percent yield based on HC] reacted.

A study of the data in table I clearly illustrates the advantages ofoperating in accordance with the process defined and claimed herein. inRuns 5 and 6 the advantage of carrying out the halogenation in thepresence of both the heavy metal catalyst and the carboxylic acidanhydride instead of either alone is clearly demonstrated. In likemanner acetic acid is convened to bromoacetic acid, propionic acid isconvened to 2-chloropropionic acid, stearic acid is converted tochlorostearic acid, caproic acid is converted to bromocaproic acid andthe like.

It should be understood that the above examples are merely illustrativeof the principles of the present invention and that variousmodifications may be made in the examples given without departing fromthe spirit and scope of the invention as defined in the followingclaims.

ganese, cerium, cobalt, vanadium, chromium, iron, nickel, cadmium, tin,antimony, mercury, bismuth, and the noble metals and compounds of thesemetals.

2. The process of claim 1 wherein said carboxylic acid charge has fromtwo to six carbon atoms.

3. The process of claim 1 wherein said halogen ion is a chloride ion.

4. The process of claim 3 wherein said halogen ion is obtained fromhydrogen chloride.

5. The process of claim 1 wherein said lower carboxylic acid anhydridehas from four to 12 carbon atoms.

6. The process of claim 5 wherein said lower carboxylic acid anhydridehas from four to six carbon atoms.

7. The process of claim 1 wherein said carboxylic acid is acetic acidand the halogenated carboxylic acid is chloroacetic acid.

8. The process of claim 1 wherein said material is a noble metalcompound.

9. The process of claim 1 wherein said material is a copper compound.

M). The process of claim 1 wherein said nitrate ion is obtained fromnitric acid.

11. The process of claim 1 wherein the reaction temperature is about toabout 150 C.

12. The process of claim 1 wherein the reaction temperature is about 60to about C.

l i t i

2. The process of claim 1 wherein said carboxylic acid charge has fromtwo to six carbon atoms.
 3. The process of claim 1 wherein said halogenion is a chloride ion.
 4. The process of claim 3 wherein said halogenion is obtained from hydrogen chloride.
 5. The process of claim 1wherein said lower carboxylic acid anhydride has from four to 12 carbonatoms.
 6. The process of claim 5 wherein said lower carboxylic acidanhydride has from four to six carbon atoms.
 7. The process of claim 1wherein said carboxylic acid is acetic acid and the halogenatedcarboxylic acid is chloroacetic acid.
 8. The process of claim 1 whereinsaid material is a noble metal compound.
 9. The pRocess of claim 1wherein said material is a copper compound.
 10. The process of claim 1wherein said nitrate ion is obtained from nitric acid.
 11. The processof claim 1 wherein the reaction temperature is about 80* to about 150*C.
 12. The process of claim 1 wherein the reaction temperature is about60* to about 120* C.